Recording head carriage guiding means



July 4, 1950 ALLEN 2,513,441

RECORDING HEAD CARRIAGE GUIDING MEANS Filed Sept. 15, 1945 Patented July 4, 1950 RECORDING HEAD CARRIAGE GUIDING DIEAN S Henry Hans Allen, London, England, assignor, by mesne assignments, to Celanese Corporation of 1 America, a corporation of Delaware Application September 15, 1945, Serial No. 616,543 In Great Britain September 19, 1944 3 Claims. (01. 274-13) 1 This invention relates to apparatus for recording sound on an endless band.

One method of recording sound consists of forming a groove, modulated in accordance with the sound to be recorded, in an endless band of suitable material, e. g. film havinga basis of cellulose acetate, the recording head carrying the groove-forming tool being slowly moved across the band so that by the time that part of the band where the groove starts again reaches the tool the latter has moved sufficiently to permit continuation of the groove to one side of the part earlier formed; the band thus appears eventually to have a number of parallel grooves formed in it side by side. The carriage on which the recording head is mounted comprises a nut threaded on to a lead screw rotation of which drives the carriage, and hence the recording head, across the band.

The invention is concerned with sound recording apparatus of the type described and, more particularly, with improved means for supporting and guiding the recording head carriage. The invention is of particular value where it is desired that the recording head should be able to move transversely but not otherwise in relation to an abutment for the band at the recording point.

According to the invention, in apparatus of the class described, the carriage for the recording head comprises a member operatively engaging the thread of a lead screw and guide means adapted to constrain the motion of the carriage to a simple rectilinear translation independently of said lead screw, whereby the function of said lead screw is limited to imparting said translation.

The construction of the present invention offers substantial advantages over previous devices, in particular in that the novel construction reduces very considerably, or even eliminates, the possibility of uneven wear on the means for feeding the head transversely during the passage of the band. When a single guide rod of circular cross-section is used as in previous devices, this guide rod acts as a pivot and consequently the weight of the recording head and its carriage is applied to one side of the lead screw which is employed for moving the head transversely and furthermore part of the cutting resistance of the band is also applied to the same part of this lead screw. In practice, this is liable'to result in the lead screw becoming slightly eccentric so that in operation the recording head, and with it the tip of the recording stylus, is moved up and 2 down and the amount of movement is equal to double the eccentricity developed on the lead screw which has a considerable eifect on the quality of the recording. By means of the present invention, it is possible to construct recording apparatus of the type described the operation of which will not be deleteriously affected in the manner indicated, even after use over an extended period.

In the accompanying drawings, which illustrate one embodiment of the invention:

Fig. 1 shows a side elevation, in part section along line |I of Figure 2, and

Fig. 2 shows a plan view, in part section along the line 2-2 of Fig. 1, of a cutting head carriage and means for supporting and guiding the carriage in accordance with the invention.

Fig. 3 shows a section along the line 3-3 of Fig. 2.

Referring to the drawings the cutting head carriage comprises the nut l, threaded on the lead screw 2 and supported and guided, independently of the lead screw, by guide rod 3 of right-triangular cross-section. The lead screw 2 is journaled at one end in a bearing 4 secured in the main panel 5 of a recording apparatus and at the other end in a bracket 6 secured to the panel by screws 1. Axial movement of the lead screw is restrained by collar 8 pinned to the plain end of the lead screw and nut 9 and locknut ID. The bracket end of the lead screw carries a handle (not shown) for manual operation of the lead screw which is normally driven by gearing (not shown) connected to the panel end of the lead screw. The guide rod 3 is secured to an eccentric bush H in panel 5 by nuts l2 threaded on to the end of the guide rod, a keyed shoulder l3 being provided on the guide rod to facilitate angular adjustment thereof, the bush ll likewise being keyed as shown to facilitate its rotation in the panel 5. The cylindrical extremity M of the guide rod remote from the panel is carried in bracket 6 which is bored to a clearance fit for the said cylindrical extremity. Nut 15 threaded on to extremity M secures guide rod 3 in place after adjustment. The nut l is threaded on to lead screw 2 and is shaped (as shown in Fig. 1) to engage the narrow faces of guide rod 3. Plate [6 is secured to nut I by screws I! so as to engage the wide face of guide rod 3. Plate I6 carries dependent lug [8 which is provided with countersunk holes 19 whereby a cutting head, or a mounting for a cutting head which provides for adjustment of the height of the cutting head, can be secured to the carriage.

Pointer 20 is secured to the nut l and arranged to co-operate with scale 2| secured to boss 22 on main panel 5 and eXtending over the path of the nut I. Conveniently the scale may carry graduations indicating the time occupied by the recording made and accordingly of the remaining time before the spoolof'film in the apparatus is fully recorded.

It will be appreciated that in the construcl0 and sliding engagement with said rod along its tion shown, angular adjustment of theguide rod 3 by rotation of keyed shoulder l'3,and adjustment of the distance between guide rod"3'a'nd lead screw 2 by rotation of 'eccentric-bush l'l,"-'a're simple to make and enablethe-position of guide rod 3 to be chosen with great accuracy'so thatthe whole weight of the carriage, as well as-the cutting head and any adjusting mechanism mounted thereon, is borne by the guide rod 3 so that, in operation, the lead screw 2 performs only the function of imparting motion to the carriage and whatever'is mounted thereon.

While the invention has been described mor e particularly in connectionwith the use of a guide rod of "triangular cross-section it will be appreciated that "the object of the invention -can b'e achieved with other constructions. Thus a gui'de rod of any cross-se'ction other than 'circularg-eg g. semi-circular, or a plurality --of parallel gnide rods of circular or other cross secti'on may -"be used.

Havingwdescribed my invention, what I desire :to'secure by Letters Patent is:

1. In apparatus for recording sound on an 'endless band-of material, the combinationbf a panel, a lead screw'rota'tably mounted thereon,

an eccentrically bored bush aXially-= adjustablein said panel, a guide rodaxiallyadjustable-insaid bush, the axes of said lea'd sc'rew -and guide'rod being parallel in a common plane for all axial positions of said bush and rod,- me'ans-for securing said' bush and rod-against a d-justment a portion-of non-circularcross-section on'said-rod,

and acarr-iage in driven engagement with sa-id lead screwandsliding engagement with said *ro'd along itsportion of non-circularcross-section.

c2; In apparatus for recordingsound on an endllessb'and of material, the combination of apan'el,

4 a lead screw rotatably mounted thereon, an eccentrically bored bush axially adjustable in said panel, a guide rod axially adjustable in said bush, the axes of said lead screw and guide rod being 5 parallel in a common plane for all axial positions -of said bush and rod, im'eans for securing said bush and ron againstadjustment,-aportion of triangular cross-section on said rod, and a carriage in driven engagement with said lead screw poi tiono'f triangular cross-section.

3. Tn apparatus for recording sound on an :endless band of :material, the combination of a panel, a lead screw rotatably mounted thereon,

I5 "an-"eecentrically bored bush axially adjustable -in-said.paneL asguide rod axially adjustable in said bushy-the axes of said lead screw and guide rod being parallel in a common plane for all axiarpositions of said bush and rod, means for go securing said bush and rod against adjustment,

a portion -:of right trian'gular caress-section on said rod, and La "carriage iin :Idriven engagement 'with said leadscrew and grooved tovprovide sliding engagement with the-two faces of the triangular portion-of "said guide rod which are at right ang-les andiaiplate carried: by the carriage ancl engagin'gi sl-idably the thircl 'face of said guid rod.

HENRY HANS ALLEN.

*REFERENGE S CITED --The-following-referencesiare of record in the -file-o'f this ,patent:

' 3 UNITED: :STATES PATENTS Number "Name 5 Date 430,759 fst. John J-une'-'24,*1 8 90 458,916 Oxley Sept. 1, 1891 1,947,290 Fonda Feb. 13, -1934 2,239,359 Banning Apr. 22, 1941 "2,293,217 'Rieber Aug.=1 8, 1 942 2350,49!) 'Bi' linel J une 6,1944

:FOREIGNPATENTS 45 Number Country Date 13 ,255 France Dec. 20, 1910 

